Multifunction domestic station, device for powering the same with hydrogen and method of operating the same

ABSTRACT

A multifunction domestic station includes a reaction chamber connected to a source of a pressurised mixture of water and air, to a first source of a first fuel capable of endothermically reacting with the mixture and to a second source of a second fuel. The station also includes heating devices capable of heating the first fuel to a combustion temperature in order to prime the reaction between the fuel and the mixture; and devices for utilising the thermal energy generated by the reaction, in order to make the station operate as an electric power generator, a heat generator and a device for the disposal of domestic wastes. A device for powering the station with the second fuel and a method of operating the station are also provided.

TECHNICAL FIELD

The present invention relates to a multifunction domestic station, to adevice for powering the same with hydrogen and to a method of operatingthe same.

More particularly, the invention relates to a domestic station havingthe functions of electric generator, heat generator and device for thedisposal of domestic wastes.

BACKGROUND OF THE INVENTION

Due to the increase in the sensitiveness to the problems of environmentprotection, in recent years a constant development has been observed inresearches concerning processes and systems for the generation of theso-called “clean” energy, that is, processes and systems which do notuse fossil fuels or other fuels generating polluting substances orsubstances that are harmful for health or difficult to be disposed.

In recent years, a development has also been observed in researchesconcerning processes and systems for high-efficiency energy generation.

For instance, a method and a device using a reaction chamber orcombustor using water and heated oil for generating energy is disclosedin patent publication WO 95/23942. The prior art device includes acombustor arranged to generate a flame which is horizontally deflectedinto a conventional boiler trough a connection.

The inventor of the prior art publication has realised that the priorart combustor has some drawbacks.

Actually, the flame of the combustor, being deflected so as to act inthe horizontally arranged boiler, is arranged to heat the connectionoutside the boiler to a greater extent than the boiler interior, therebycausing a high loss of heat that could otherwise be exploited.

Moreover, the connection between the combustor and the boiler is apossible source of danger for the operators, who can burn themselves incase of contact with the connection, which is incandescent in use.

It is the object of the invention to provide a multifunction domesticstation, a device for powering the same and a method of operating thesame, which have high performance and which can be industriallymanufactured at low cost.

DESCRIPTION OF THE INVENTION

In accordance with a first aspect of the invention, the stationcomprises a structure including a combustor in which an endothermicreaction of at least one fuel with water is exploited in order togenerate high temperature thermal energy.

The combustor is configured so as to directly direct the thermal energy,for instance a vertical flame, towards utilisation devices, such as aboiler external to the combustor and/or a boiler internal to thecombustor.

The provision of one or multiple boilers onto which the thermal energygenerated within the combustor is directly directed allows attaining aparticularly high efficiency, without heat losses.

The combustor or reaction chamber is connected to a source of apressurised mixture of water and air and at least to a source of a firstfuel capable of endothermically reacting with the mixture.

The domestic station further includes heating devices for heating thefirst fuel to a combustion temperature in order to prime the reaction.

According to a first embodiment of the invention, the source of thefirst fuel, which is a vegetal or mineral oil, preferably exhausted, isconnected to the reaction chamber both during a reaction priming phaseand during a reaction maintaining phase, so that a reaction between theexhausted oil and the water-air mixture takes place in both phases.

According to another embodiment of the invention, the station alsoincludes a source of a hydrogen-containing second fuel, which source isconnectable to the reaction chamber, during the reaction maintainingphase, in the alternative or in addition to the source of the firstfuel.

In accordance with another aspect of the invention, the station includesa hydrogen generator utilisable as the source of the second fuel. Thegenerator comprises one or more units, each including:

a chamber for the electrolytic decomposition of water, the chamber beinginternally equipped with a plurality of elements of conductive material,which are electrically connected in series with one another and with apulsed voltage generator; anda pressurised container, connected on the one side to the decompositionchamber for receiving therefrom water, hydrogen and other products ofthe electrolytic decomposition and for introducing again pressurisedwater into the chamber, and connected on another side to the reactionchamber of the station in order to feed the chamber with hydrogen andthe other products of the electrolytic decomposition.

According to a preferred embodiment of the invention, the pulsed voltagegenerator includes a d.c. voltage source, such as a battery or anaccumulator, connected to a generator of a sawtooth voltage.

In accordance with a further aspect of the invention, a method ofoperating the station comprises bringing a pressurised mixture of waterand air into contact with a fuel capable of endotheimically reactingwith the mixture, after the fuel has been heated to a combustiontemperature in order to prime the reaction between the fuel and themixture.

In a reaction priming phase the fuel is a vegetal or mineral oil,preferably exhausted, and in a reaction maintaining phase the fueleither can be the oil or it is hydrogen (more precisely, ahydrogen-containing fuel) or an oil-hydrogen mixture.

BRIEF DESCRIPTION OF THE FIGURES

Further features of the invention will become apparent from thefollowing description of preferred embodiments, given by way of nonlimiting examples with reference to the accompanying drawings, in which:

FIG. 1 is a principle diagram of a station according to the invention;

FIG. 2 a is a principle diagram of a variant;

FIG. 2 b is a schematic representation of the station shown in FIG. 2 a;and

FIG. 3 is a diagram of a hydrogen generator utilisable in the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, the multifunction domestic station according to theinvention, generally denoted by reference numeral 1, includes a reactionchamber or combustor 11 equipped with an exhaust terminal 1 la at anupper end of the chamber. A strongly endothermic reaction takes place inchamber 11 between water, preferably source water at ambienttemperature, and a preheated fuel. In this embodiment, the fuel is anoil (either a vegetal oil, for instance seed oil, olive oil and so on,or a mineral oil, for instance oil for engines or hydraulic oil), whichis preferably exhausted so as to limit its cost.

Chamber 11 is preferably shaped as a frustum of a cone or a pyramid withsquare base and has exhaust terminal 1 la at its top end. Such astructure assists in maintaining the water-fuel reaction within thechamber upon multiple reflections, thanks to the kinetic energygenerated, so as to create a rotating fire ball which does not leaveimmediately the chamber through exhaust terminal 11 a and therefore hasthe necessary time to burn possible residuals of the endothermicreaction, thereby drastically reducing or eliminating them and/orraising at the same time the operating temperature of the chamber.

In any case, the chamber might also be prismatic, without therebydeparting from the scope of the invention as described and claimed, andit may preferably have a base size in the range 15×15 cm to 200×200 cmand a height in the range 15 cm to 200 cm.

The endothermic reaction preferably generates a flame that, in allembodiments, vertically leaves the chamber through exhaust terminal 11a.

The fuel is contained in a tank 12, for instance a gravity tank with anelectrically operated valve 12 a, and is preferably sent to reactionchamber 11 by means of a pump 13.

Tank 12 is moreover associated in conventional manner with leveldetectors 22, arranged to monitor the filling level of tank 12 and tooperate an external pump (not shown) when it is necessary to supplyagain the tank with fuel. Other level detectors 23 are advantageouslyassociated with reaction chamber 11 and are arranged to act on pump 13so as to keep the fuel level within chamber 11 between a minimum and amaximum ensuring the optimum station operation. Taking into account thatthe reaction generates very high temperatures, as it will be betterdisclosed below, detectors 23 can for instance include a laser devicearranged outside chamber 11, or they may be detectors immersed in thefuel.

Reaction chamber 11 is further associated with two burners 14, 15. Thefirst burner 14 (priming burner) is a conventional burner, for instancean oil or gas burner, and is to preheat the oil at such a temperature asto cause combustion thereof. The second burner 15 (reaction maintainingburner) is instead to send a pressurised water-air mixture, typically ata pressure of the order of 0.5-1 bars, into reaction chamber 11 afteroil firing. In the alternative, burner 15 may be replaced by acompressed air ejector, operating at a pressure of a few bars, forinstance 3-4 bars, and it is associated with a Venturi for air suction.

Two operation phases are therefore provided. In the first phase (primingphase), oil is brought to a combustion temperature that will depend onthe particular kind of oil being used and, generally, will be in therange of about 350° C. to 450° C. In the second phase (reactionmaintaining phase), the water-air mixture is introduced into chamber 11.When the mixture comes into contact with the burning oil, a strongreaction at very high temperature occurs, resulting in waterdissociation and consequent development of atomic and molecularhydrogen, oxygen and H⁺ and OH⁻ ions, as experimentally verified by theinventor.

An explanation of this behaviour could be the occurrence of a mechanicaleffect combined with different levels of sequential reactions andexpansions at atomic level inside chamber 11, which effect creates anactual thrust in exhaust terminal 11 a with a temperature, measured inopen air, of about 1500° C.-1600° C. and a noise of 100-120 db, asexperimentally verified by the inventor. The noise and the exit pressureof the reaction products will obviously depend on the size of exhaustterminal 11 a.

A confirmation of the hypothesis of occurrence of a reaction at theatomic level and not of a chemical reaction is given by the emission ofUV radiation noticed during the experimental tests.

Due to such high temperatures, polluting substances are practicallyabsent, or are present in negligible amounts, in the gases produced bythe combustion and leaving the chamber through exhaust 11 a.Measurements carried out by the inventor have actually shown that CO₂and nitrogen oxides NO_(x) are present in amounts of a few parts permillion (2-3 ppm for CO₂, 5-10 ppm for NO_(x)):

Devices for utilising the thermal energy, denoted in the whole byreference numeral 16, are directly connected to exhaust 11 a ofcombustion chamber 11, said devices being configured so as to exploitthe thermal energy produced by the reaction.

More particularly, devices 16 may include a steam producing device(boiler) 17, followed by a conventional turbine 18 (in this case, asteam turbine) made to rotate by the steam produced in boiler 17.Turbine 18 is in turn connected for instance to one or more alternators19 for generating electric power for domestic use, for instance at 3 to5 kW/h per generator.

In accordance with a variant of the embodiment deemed as preferred, asecond boiler 17 a is located inside reaction chamber 11. Such anembodiment allows a double exploitation of the energy generated by theendothermic reaction.

In alternative or in addition to the devices connected to exhaust 11 a,devices 16 could include a heat exchanger 20, for instance a coilsurrounding reaction chamber 11, for heating water to be used in aheating plant, as sanitary hot water for domestic use etc.

In accordance with yet other embodiments, the steam generated in theboiler, for instance the steam generated in the first boiler 17 and usedto drive turbine(s) 18, upon being condensed into water and before beingsent to a collecting container, is used for being applied in heatingplants, for instance plants with radiators, or for producing hot water,and then is cooled through a heat exchanger before entering the watersupply container for boiler 17.

Preferably moreover, a drawer or other container 21 is inserted betweenreaction chamber 11 and boiler 17, said container (of course made of amaterial resistant to the high temperatures mentioned above) beingarranged to contain domestic wastes, in particular wastes that cannot besubjected to differentiated collection and hence recycled. Preferably,the drawer is arranged inclined towards a grate exposed to the flame sothat the wastes, exposed to the high temperatures generated by thereaction, burn substantially without emitting polluting and poisonoussubstances, such as dioxin, and with a negligible emission of theabove-mentioned CO₂ and NO_(x). The station can therefore also be usedas a domestic waste-to-energy plant.

FIGS. 2 a and 2 b show a second embodiment of the invention, denoted 1A.The elements already disclosed with reference to FIG. 1 are denoted bythe same reference numerals.

In this second embodiment, oil coming from tank 12 is still used as thefuel in the reaction priming phase, whereas oil, or an oil-hydrogenmixture, containing for instance 70% oil and 30% hydrogen, or yet onlyhydrogen can be used as fuel in the reaction maintaining phase. Hydrogenis produced for instance by at least one hydrogen generator 25.

In case of use of a fuel containing the mixture of oil, for instanceexhausted oil, and hydrogen, the inventor has noticed a yield 50% higherthan that attainable when using only oil as the fuel.

Simultaneous use of both fuels allows arranging at least two electriccurrent generators or alternators 19 at the output of boiler 17, forinstance by connecting a pulley arranged to operate the alternators bymeans of toothed wheels to turbine 18.

In case hydrogen is used as fuel in the maintaining phase, electricallycontrolled valve 12 a is closed thereby isolating tank 12 from reactionchamber 11, pump 13 is not operated, and hydrogen and the pressurisedwater-air mixture are sent to chamber 11.

Preferably, at least a pair of identical generators 25 is provided, asshown in FIG. 2 a. Assuming for instance that two generators areprovided, one of them can be a stand-by generator, arranged to intervenein case of failure of the other generator. The generators can however beused in alternating manner, according to a suitable timing, or jointly,for instance to meet peaks of power demand.

In all embodiments, devices arranged to detect the value of the flametemperature in reaction chamber 11 can be preferably provided. Suchdevices can be connected to means for automatically turning off thestation in case of anomalous operation.

Preferably, the station comprises a control panel including, forinstance, instruments for measuring temperature and pressure values inthe various components of the station.

Moreover, for safety reasons, non-return valves, pressure switches andother safety devices might also be provided in the station.

The structure of generator 25 is shown in greater detail in FIG. 3.

The generator comprises a chamber 30 for the electrolytic decompositionof demineralised water, with a duct 21 for supplying the demineralisedwater, made conductive preferably by the addition of alkaline metalcompounds, preferably hydroxides of such metals, in particular sodiumhydroxide or, in the alternative, potassium hydroxide. The water mightalso contain concentrated hydrogen peroxide added in a percentage of upto 50%, for instance 10 to 50%. The addition of hydrogen peroxide allowsincreasing the amount of hydrogen produced for a given size of chamber30.

A set of elements 32 of conductive material, for instance stainlesssteel and/or titanium, are arranged within chamber 30. Elements 32, forinstance discs or plates (“discs”) are coaxially mounted on one or morerods 33 (for instance a central rod, as shown in the Figure, or aplurality of rods distributed along the periphery of discs 32) and areseparated by spacers 34, for instance a few millimetres thick (e.g. 1-2mm thick). Discs 32 have a slightly smaller size than chamber 30 anddefine with the side walls of the chamber a substantially serpentinepath for water.

Preferably, the serpentine path for water is obtained by inserting, atthe end of each disc 32, suitable sealing rings or components 32 a ofplastic material, e.g. Teflon, fastened to decomposition chamber 30, andby providing one or more throughholes 52 on each disc 32, the holes inadjacent discs 32 being located in diametrically opposed positions.

Discs 32 are electrically connected in series with one another and witha generator of d.c. voltage, for instance a battery or accumulator 41(typically, a motor-car battery with 12 V nominal voltage or anindustrial vehicle battery with 24 V nominal voltage), and a wall ofchamber 30, in particular roof 30 a, serves as the ground. The voltagesource is such as to establish a same voltage difference, in particulara voltage difference of about 2 V and preferably in the range 2.1 to2.35 V, between a first disc 32 in the plurality and ground 30 a andbetween adjacent discs 32. With such values of the voltage difference,at least six discs 32 are provided, since a nominal voltage lower than12 V does not allow a good operation of the generator. The actual numberof the discs will depend on the voltage generated by battery 41.

Means 42 are arranged between battery 41 and the set of discs 32 forconverting the d.c. voltage generated by battery 41 into a pulsedvoltage, for instance a sawtooth voltage having a maximum valuecorresponding to the nominal voltage of the battery, whereas the minimumvalue can preferably be in the range 40% to 50%, and preferably is about50%, of such a nominal voltage.

Such a pulsed voltage causes the formation on the surface of discs 32,due to water decomposition, of small hydrogen bubbles the sizes of whichincrease as the voltage applied to the individual discs increase (andhence as water proceeds within chamber 30 by following the serpentinepath).

At the end of the serpentine path, in correspondence with the last disc32, the small hydrogen bubbles attain, due to the surface tension, suchsizes that they can detach themselves from the surface of the same disc.The above-mentioned voltage difference of about 2 V between adjacentdiscs is the optimum value for creating those bubbles.

Water and the products of electrolytic decomposition (hydrogen, oxygenand H⁺ and OH⁻ ions) leave chamber 30 through a duct 35 and are fed to apressurised container 37 (for instance at 2-3 bars), possibly through aradiator 38 arranged to cool the products of electrolytic decomposition.

In the alternative, especially in case of small plants, cooling can beperformed by means of d.c. powered cooling fans, for instance of thekind used in personal computers.

Gaseous products and ions, which are more volatile, leave container 37through a top duct 39 leading to reaction chamber 11 (FIGS. 1, 2 a, 2b), whereas demineralised water is introduced again under pressure intoelectrolytic decomposition chamber 30 through a bottom outlet duct 40and a pump 36.

In accordance with a constructional variant of generator 25, a protonaccelerator, for instance of the kind disclosed in patent publication WO2007/119141 A in the name of the inventor, is located at the exit fromtop duct 39 leading the hydrogen compound from the generator tocombustion chamber 11. Said accelerator is capable of increasing theyield of generator 25, as experimentally verified by the inventor,

In an advantageous embodiment, the gases are heated before beingintroduced into reaction chamber 11 (for instance by using coil 20mentioned above), thereby creating a pressure and volume increase and astronger suction of the same gases. In this case, duct 39 will have tobe associated with a non-return valve (not shown), for preventinghydrogen and the other products of electrolytic decomposition, whichhave undergone the pressure and volume increase due to the heating, fromgoing back into container 37.

Sending the products of electrolytic decomposition into reaction chamber11 facilitates the high temperature reaction.

Taking into account the description of generator 25, it is pointed outthat, when the use of hydrogen as fuel has been referred to in thedescription of the station, the term “hydrogen” denotes, more generally,the whole of the products of the electrolytic decomposition of water.

It is to be appreciated that, due to the use of the alkaline metalcompounds, the components of generator 25 are not to contain aluminium,which would be attacked by said compounds.

The advantages afforded by the invention are clearly apparent from thepreceding description.

The basic reagents are cheap (essentially water, alkaline compounds andexhausted oils) and hence the whole process and the station can becarried out/manufactured and managed in economical manner.

The very high temperatures attained allow attaining high performance.Moreover, as said, at the temperatures indicated, the reaction fumescontain negligible amounts of polluting substances.

Using exhausted oils as fuel at least in the reaction priming phase alsocontributes to the disposal of such oils.

Moreover, the possibility of using the station as waste-to-energy plantassists in eliminating wastes that cannot be recycled.

Furthermore, it is not to be neglected that the management costs of thedomestic station as described are extremely low thanks to the use ofliquid fuel of little value, such as exhausted oils, and/or of gasesobtained from the decomposition of demineralised water, which in turn isa cheap resource.

Moreover, advantageously, the station can be configured so as to allow,for instance, heat production, electric power production and wastedisposal.

In synthesis, a domestic station is provided that can be installed inevery house as a one-family plant or as a central plant, for instance acondominium plant, in order to provide a plurality of services at verylow cost.

By summarising, the station of the invention is actually a completelyautonomous and stand-alone equipment and not only a component of a morecomplex system.

It is clear that the above description has been given only by way ofnon-limiting example and that changes and modifications are possiblewithout departing from the scope of the invention as defined in thefollowing claims.

1.-15. (canceled)
 16. A multifunction domestic station, comprising: areaction chamber connected to a source of a pressurised mixture of waterand air, at least to a first source of a first fuel capable ofendothermically reacting with the mixture and to at least one secondsource of a second fuel; heating devices capable of heating the firstfuel to a combustion temperature in order to prime the fuel reactionwith the mixture; and devices for utilising thermal energy generated bythe reaction, so as to build a completely autonomous and stand-aloneequipment.
 17. The station as claimed in claim 16, wherein the firstsource of the first fuel is arranged to supply the reaction chamber withan oil, preferably an exhausted oil, and is connected to the reactionchamber at least during a reaction priming phase.
 18. The station asclaimed in claim 16, wherein said second fuel is used, in thealternative or in addition to the first fuel, during a reactionmaintaining phase, said second fuel comprising hydrogen.
 19. The stationas claimed in claim 17, wherein said second fuel is used, in thealternative or in addition to the first fuel, during a reactionmaintaining phase, said second fuel comprising hydrogen.
 20. The stationas claimed in claim 16, wherein the devices for utilising the thermalenergy include one or more devices selected from: a boiler connected toan exhaust of the reaction chamber; a turbine, operated by the steamgenerated by the boiler and arranged to operate one or more electricpower generator(s); a heat exchanger for producing hot water and/or forheating hydrogen, when the latter is used; a container for domesticwastes burning when exposed to the thermal energy generated by thereaction, the container being located between the reaction chamber andthe boiler.
 21. The station as claimed in claim 17, wherein the devicesfor utilising the, thermal energy include one or more devices selectedfrom: a boiler connected to an exhaust of the reaction chamber; aturbine, operated by the steam generated by the boiler and arranged tooperate one or more electric power generator(s); a heat exchanger forproducing hot water and/or for heating hydrogen, when the latter isused; a container for domestic wastes burning when exposed to thethermal energy generated by the reaction, the container being locatedbetween the reaction chamber and the boiler.
 22. The station as claimedin claim 18, wherein the devices for utilising the thermal energyinclude one or more devices selected from: a boiler connected to anexhaust of the reaction chamber; a turbine, operated by the steamgenerated by the boiler and arranged to operate one or more electricpower generator(s); a heat exchanger for producing hot water and/or forheating hydrogen, when the latter is used; a container for domesticwastes burning when exposed to the thermal energy generated by thereaction, the container being located between the reaction chamber andthe boiler.
 23. The station as claimed in claim 20, wherein the devicesfor utilising the thermal energy also include a boiler located withinthe reaction chamber.
 24. The station as claimed in claim 16, whereinsaid reaction chamber is configured so as to directly direct the thermalenergy towards the utilising devices.
 25. The station as claimed inclaim 17, wherein said reaction chamber is configured so as to directlydirect the thermal energy towards the utilising devices.
 26. The stationas claimed in claims 18, wherein said reaction chamber is configured soas to directly direct the thermal energy towards the utilising devices.27. The station as claimed in claim 24, wherein said thermal energy isin the form of a flame vertically leaving the reaction chamber.
 28. Agenerator of hydrogen to be used as fuel in a multifunction domesticstation of a kind exploiting an endothermic reaction of hydrogen with awater and air mixture in order to generate heat at high temperatures,said station including: reaction priming means, arranged to heat avegetal or mineral oil, preferably exhausted, to a combustiontemperature; and reaction maintaining means, fed with a hydrogen-basedfuel; the hydrogen generator being characterised in that it includes atleast one hydrogen generating unit in turn including: a chamber for theelectrolytic decomposition of demineralised water, the chamber beinginternally equipped with a plurality of elements of electricallyconductive material, which are electrically connected in series with oneanother and with a generator of a pulsed voltage; and a pressurisedcontainer, connected on one side to the electrolytic decompositionchamber for receiving therefrom water, hydrogen and other products ofthe electrolytic decomposition and for introducing again the pressurisedwater into the chamber, and connected on another side to a reactionchamber of the station in order to feed the chamber with hydrogen andthe other products of the electrolytic decomposition.
 29. The generatoras claimed in claim 28, wherein the generator of a pulsed voltageincludes a d.c. voltage source connected to a generator of a sawtoothvoltage having a maximum value corresponding to a nominal value of thed.c. voltage and a minimum value corresponding to a fraction of saidnominal value, the generator of a pulsed voltage being capable ofestablishing a same voltage difference between a first element in theplurality of elements of electrically conductive material and a groundand between adjacent elements of electrically conductive material. 30.The generator as claimed in claim 28, wherein an outlet duct of thepressurised container connecting such container to the reaction chamberis equipped with means for heating hydrogen and the other products ofthe electrolytic decomposition before they are introduced into thereaction chamber, and with means for preventing hydrogen and the otherproducts of the electrolytic decomposition having undergone a pressureincrease due to the heating from returning into the container.
 31. Thegenerator as claimed in claim 28, wherein said plurality of elements ofelectrically conductive material are made by discs or plates having aslightly smaller size than the electrolytic decomposition chamber. 32.The generator as claimed in claim 31, wherein each disc or plate isconfigured so as to define a serpentine path for the demineralised waterinside the electrolytic decomposition chamber.
 33. A method of operatinga multifunction domestic station, comprising bringing a pressurisedmixture of water and air, within a reaction chamber, in contact with afirst fuel capable of endothermically reacting with the mixture, afterthe fuel has been heated to a combustion temperature in order to primethe reaction between the mixture and the fuel, and maintaining thereaction by introducing a second fuel into the reaction chamber so as toobtain thermal energy generation.
 34. The method as claimed in claim 33,wherein: the first fuel for the reaction priming phase is a vegetal ormineral oil, preferably exhausted; and the second fuel for the reactionmaintaining phase is hydrogen or gases obtained from the decompositionof demineralised water; and wherein: said phase of thermal energygeneration is used in utilising devices configured for utilising thethermal energy generated by the reaction.
 35. The method as claimed inclaim 34, wherein the thermal energy generated by the reaction is usedfor: generating electric power; and/or being applied in heatinginstallations; and/or generating hot water to be used for producingsanitary hot water for domestic use; and/or preheating hydrogen or thegases obtained from the decomposition of demineralised water; and/orburning domestic wastes.